Mobile networks, such as according to the GSM or UMTS standards are set up in a cellular manner. This means that a mobile network comprises cell towers, so called base stations. Such base stations have a coverage area adapted for receiving radio signals from a mobile station and transmit corresponding signals in return. This coverage area of a base station forms a mobile network cell. Furthermore, such mobile network cells may overlap. Commonly, different frequencies are used in adjacent mobile network cells in order to avoid overlapping or interferences.
However, there are known systems where several base stations simultaneously receive signals from mobile stations. With such an overall cellular cooperative detection of signals a signal is received depending on the position of the mobile station where each of the participating base stations receives a different signal which depends on the damping and the run time. Using the same data transmission resource, such as, for example, the same frequency or the same time window, for several mobile stations a superimposed or interfered signal can be received by each base station. This received superimposed signal comprises the corresponding signals of all mobile stations using the same transmission resource.
With suitable methods the signals of each individual mobile station can be filtered out from the superimposed received signals of the participating base stations. For this purpose the respective superimposed signals received by the various base stations must be collected and processed. Normally, the received superimposed signals of each base station are digitized and forwarded to a central processing unit. The central processing unit can be provided in a base station or separately in the mobile network. The superimposed signals are compared in the central processing unit and the received signal of each mobile station is filtered out. Then, a corresponding wanted/useful signal is decoded from the received signal of each participating mobile station. This method causes improvement of the achievable data transmission rates of participating mobile stations.
The considerable data transfer between the base stations and the central processing unit is disadvantageous with the known methods for the overall cellular, cooperative detection of signals of a plurality of mobile stations using the same transmission resource. In order to centrally process and decode the superimposed signals received by all participating base stations they are digitized and transmitted through network connections to the central processing unit. Due to this large data volume the network resources are stressed very much. If necessary, further transmission capacity must be installed, bought or rented which is very costly.